Information access in a dual-task context: testing a model of optimal strategy selection

Pilots were required to access information from a hierarchical aviation database by navigating under single-task conditions (Experiment 1) and when this task was time-shared with an altitude-monitoring task of varying bandwidth and priority (Experiment 2). In dual-task conditions, pilots had 2 viewports available, 1 always used for the information task and the other to be allocated to either task. Dual-task strategy, inferred from the decision of which task to allocate to the 2nd viewport, revealed that allocation was generally biased in favor of the monitoring task and was only partly sensitive to the difficulty of the 2 tasks and their relative priorities. Some dominant sources of navigational difficulties failed to adaptively influence selection strategy. The implications of the results are to provide tools for jumping to the top of the database, to provide 2 viewports into the common database, and to provide training as to the optimum viewport management strategy in a multitask environment.     

False memories and statistical decision theory: comment on Miller and Wolford (1999) and Roediger and McDermott (1999)

In an analysis of H. L. Roediger and K. B. McDermott's (1995) false-memory paradigm, M. B. Miller and G. L. Wolford (1999) argued that falsely recognized items occur because a bias toward calling such items "old" is created by their membership in a studied category. This interpretation was contested by Roediger and McDermott (1999). The authors of this article approach this issue as a statistical decision problem and observe that an explanation of false memory based on stored strengths and one based on decision process can have identical implications for data. Problems with equivalent formal models of this type can frequently be resolved by looking at the effects of other variables on the fitted estimates. The authors illustrate this analysis by examining the effects of presentation duration on the parameter estimates produced by models that instantiate the 2 explanations. Although the question remains open, the storage-based interpretation was found to be somewhat more plausible.     

Paradigm shifts: new techniques to answer new questions

The advent of a multiple-channels approach to spatial vision 20 years ago raised important questions that were difficult to approach empirically, given the technology and analytic tools of the time. These questions concerned the interaction or combination of different components of a stimulus--questions that have recently resurfaced in more complex form. Classical psychophysical methods for assessing whether two stimulus aspects are coded independently (e.g., masking, adaptation, and cue-summation) provide only limited information about the nature of whatever interactions are discovered. In both older work in detection and recent work in complex pattern discrimination, we have used a double-judgment paradigm in which the observer rates two aspects of a stimulus simultaneously. The paradigm provides a rich source of information about the codes underlying each psychophysical decision and which are unique in permitting us to psychophysically investigate effects resulting from neural noise in the system. Our analyses draw on theories of dimensional interaction in signal detection theory and in information theory, and on methods from several branches of statistics, including categorical data analysis and structural equation modeling. We review the theoretical, technological, methodological, and personal influences that led us to develop this approach.     

Situation Awareness and Workload in Aviation

A pilot faces special challenges imposed by the need to control a multivariate lagged system in a heterogeneous multitask environment. The time lags between critical variables require prediction in an uncertain world. The interrelated concepts of situation awareness and workload are central to aviation psychology. Three components of situation awareness are spatial awareness, system awareness, and task awareness. Each of these components has real–world implications, spatial awareness for instrument displays, system awareness for keeping the operator informed about actions that have been taken by automated systems, and task awareness for attention and task management. Task management is directly related to mental workload, as the competing demands of tasks for attention exceed the operator's limited resources.     

Hypothalamo-Pituitary-Adrenocortical Regulation Following Lesions of the Central Nucleus of the Amygdala

Previous reports indicate that the central nucleus of the amygdala (CeA) stimulates adrenocorticotropin and corticosterone secretion, suggesting a role for this region in central hypothalamo-pituitary-adrenocortical (HPA) stress regulation. To evaluate this hypothesis, this study assessed the impact of CeA lesion on the response of hypophysiotrophic paraventricular nucleus (PVN) neurons to acute restraint and chronic unpredictable stress exposure. In contrast to previous reports, CeA lesions did not affect corticosterone or ACTH secretion induced by acute stress. Acute restraint increased PVN corticotropin releasing hormone (CRH) mRNA expression, increased the number of parvocellular PVN neurons expressing the co-secretagogue arginine vasopressin (AVP), and induced cFOS mRNA expression in the parvocellular PVN. However, there was no additional effect of CeA lesion on any measure of PVN activation. Chronic unpredictable stress exposure induced long-term activation of the HPA axis, noted by thymic involution, adrenal hypertrophy and increased PVN CRH mRNA expression. Stress-induced changes in thymus and adrenal weights were not affected by CeA lesion. Further, CeA lesion rats did not differ from controls in post-stress CRH mRNA expression. However, basal CRH mRNA expression was increased in the PVN of CeA rats, suggesting that the CeA plays a role in long-term inhibition of the PVN. The results of these studies are not consistent with the hypothesis that the CeA is necessary for stress-induced pituitary-adrenocortical activation. Rather, this region may play a stressor-specific modulatory role in regulation of HPA function.     

Visual scanning with or without spatial uncertainty and divided and selective attention.

An experiment was conducted to address the relation between theories of selective attention and theories of divided attention by examining the pattern of task interference between visual scanning as a sequential and selective attention process and other concurrent spatial or verbal processing tasks. A distinction is proposed between visual scanning with or without spatial uncertainty regarding their possible differential effects on interference with other concurrent processes. The experiment required the subjects to perform a primary tracking task, which was concurrently performed with a secondary spatial or verbal decision task. The relevant information that was needed to perform the decision tasks was displayed with or without spatial uncertainty. The results provide evidence that visual scanning as a spatial exploratory activity produces greater task interference with concurrent spatial tasks than with verbal tasks. Furthermore, spatial uncertainty in scanning is identified to be the crucial factor in producing this differential effect.     

The retrieval of scaled English consonants

Two scales of the perceptual differences among English consonants had been constructed earlier, one from pairs of aural syllables and one from pairs of viewed one-syllable English words. In both instances the pairs of stimuli differed only in the initial consonants. In the present work 276 pairs of syllables were assembled in sets of six. A set was viewed sequentially for 1.5 sec/slide. Then 25 subjects who worked in groups of 4–6 attempted to write one randomly chosen omitted member of each pair on an answer form; another 25 subjects were asked to supply the opposite syllables of each pair. This task was termed primary memory. Fifty additional subjects repeated the tasks but spent 10 sec counting backward by 3s before trying to recall and write the missing syllables, thus setting up a task of secondary memory. Response forms were scored for right, wrong, and omitted responses. All responses were then compared with each of the scales referred to above, and the mean value for each group of 50 subjects (25 who used the anser form in theab order+ 25 who used theba order) was computed. The difference between the scores for the two tasks was statistically significant, as was the difference between the scores yielded by the two scales. The visual scale appeared to fit the data better than the aural scale. The procedures employed and the assumptions that were made yielded results that would not justify an opinion that an error in recall is typically almost right. However, the data did reflect partial forgetting.